A significant cause of many illnesses has long been known to involve the transmission through skin contact of bacteria, germs, microorganisms, viruses and other deleterious substances. From sniffing coworkers to raw chicken on a kitchen cutting board, every day life is full of potential infectious disease hazards. Infectious diseases typically spread through two types of contact. With direct contact, infectious disease can be spread in three different ways. The most common way for infectious disease to spread is through the direct transfer of bacteria, viruses or other germs from one person to another. This can occur when an individual with the bacterium or virus touches or coughs on someone who is not infected. These germs can also spread through the exchange of body fluids from sexual contact or a blood transfusion.
Many household pets also carry a variety of germs. Being bitten or scratched by an infected animal can make a person sick and, in extreme circumstances, could even cause death. Handling animal waste can be hazardous, too. In a third type of direct contact, a pregnant woman may pass germs that cause infectious diseases to her unborn baby. Germs can pass through the placenta, as is the case of the AIDS virus and the toxoplasmosis parasite. Or germs could spread during labor and delivery, as is the case for a mother infected with group B streptococcus.
Disease-causing organisms can also be passed along by indirect contact. Many germs can linger on an inanimate object, such as a tabletop, doorknob or faucet handle. When a person touches the same doorknob grasped by someone ill with the flu or a cold, for example, it is possible to pick up the genus the infected person left behind. By subsequently touching one's eyes, mouth or nose, the uninfected person may become infected. Some infections occur from organisms that naturally live in the environment but are not passed from person to person. Examples include fungal infections like histoplasmosis or blastomycosis, as well as bacterial infections such as anthrax.
Infectious diseases can also spread through the air. For example, when a person coughs or sneezes, droplets are expelled into the air. When that person is sick with a cold or the flu—or any number of other illnesses—these droplets contain the germ-causing illness. Spread of infectious disease in this manner is called droplet spread or droplet transmission. Droplets travel only about three feet because they're usually too large to stay suspended in the air for a long time. However, if a droplet from an infected person comes in contact with your eyes, nose or mouth, you may soon experience symptoms of the illness. Crowded, indoor environments may promote the chances of droplet transmission—which may explain the increase in respiratory infections in the winter months.
Some disease-causing germs travel through the air in particles considerably smaller than droplets. These tiny particles remain suspended in the air for extended periods of time and can travel in air currents. If you breathe in an airborne virus, bacterium or other germ, you may become infected and show signs and symptoms of the disease. Colds caused by viruses, influenza and tuberculosis are a few types of infectious diseases usually spread through the air, in both particle and droplet forms.
Some germs rely on insect carriers—such as mosquitoes, fleas, lice or ticks—to move from host to host. These carriers are known as vectors. Mosquitoes can carry the malaria parasite or West Nile virus, and deer ticks may carry the bacterium that causes Lyme disease.
The vector-borne spread of germs happens when an insect that carries the germ on its body or in its intestinal tract lands on you or bites you. The germs move into your body and can make you sick. Sometimes the germs that cause infectious disease need the insect for specific biological reasons. They use the insect's body to multiply, which is necessary before the germs can infect a new host.
Another way disease-causing germs can infect you is through contaminated food and water. Sometimes called common-vehicle transmission, this mechanism of transmission allows germs to be spread to many people through a single source. Food is often the vehicle that spreads the germs and causes the illness. For instance, contamination with Escherichia coli (E. coli) is common. E. coli is a bacterium present in or on certain foods—such as undercooked hamburger or unwashed fruits or vegetables. When you eat foods contaminated with E. coli, chances are you'll experience an illness—sometimes referred to as food poisoning.
According to many experts, including the Centers for Disease Control, hand washing is the single most effective way to prevent the spread of infectious diseases. However, when the convenience of soap and water is not readily available, hand washing may not be an option. Skin disinfectants that do not require the application of water have therefore been developed in response to the need for a skin disinfectant that is effective and easy to use. However, many of these skin disinfectants use alcohol as the primary antimicrobial agent. This is problematic because the effective concentration of alcohol, especially ethanol, generally believed to about greater than about 60% by weight, is irritating to the skin and can cause dryness with resultant peeling and cracking. Because chapped skin tends to be more susceptible to microbial contamination, repeated use of alcohol disinfectants can exacerbate the very problem they are intended to solve. Benzethonium chloride has also been used in known skin disinfectants. However, the antimicrobial activity of benzethonium chloride is easily inhibited by polysorbates and anionics that are commonly used in skin disinfectant formulations. There is therefore a need in the art for an antimicrobial composition that is effective as a skin disinfectant but does not cause increased irritation to the skin of the average user.